Affordable NAS DR in Minutes from the Cloud
Disaster Recovery is just as important for file services (NAS) as it is for structured data (databases), but it’s often neglected. Like backups, if you don’t have a loss situation, you can get by with a poor NAS DR strategy, and may not know it’s inadequate. But the DR options available aren’t always the most effective, or cost-effective. Cloud-based file services can offer some attractive benefits and features, but the recovery can still be a problem as the time or cost to replace a failed NAS system may be unacceptable. Cloud-based NAS systems that run as a virtual machine offer an alternative solution providing affordable NAS DR in a few minutes.
The symptoms of corporate data growth are often the expansion of NAS devices or the expansion of file server capacity. Some portions of these unstructured data sets can be essential to the operation of the business, so providing effective DR is as important for file services as it is for mission critical databases. Regulatory compliance can also impact NAS DR requirements. File system data does have a few more storage options available, like cloud storage, than a typical high transaction database application. But each option must be evaluated in terms of its DR implications, not just the usual factors of cost, scalability, feature set, etc.
Thursday, January 6, 2011
Backpack DR
For some organizations, the NAS DR strategy consists of copying essential files to a backup tape or removable disk drive and carrying it offsite. While effective, obviously this simplistic method is not for everyone and recovery requires getting another file server up and running. For companies that want a more sophisticated system, traditional backup to tape or backup to disk and then tape is often used. In these environments an offsite service is frequently employed to take backups to a vault and to bring the tapes back in a DR situation. When this happens, the recovery must wait for tapes to be delivered, at which point the restore process from the backup application can be used to bring files back into the replacement NAS or file server. This strategy involves a fairly complex process of getting tapes returned from offsite, then restoring data from backup.
Replication
Remote replication offers a way to get large file system data sets offsite, automatically, skipping the tapes altogether, or at least the physical transportation of tape cartridges. It can also be implemented without relying on the backup process if the source and target file servers are synchronized with replication software. But this requires that duplicate hardware, or at least comparable hardware be bought for the DR site. On the recovery side, the replication back to the primary NAS could be done at the file system level, skipping the restore process from the backup application. But for the typical volume replication processes, the entire data set must be brought back, which involves either a large bandwidth connection, a long recovery window or physically transporting the offsite NAS to the primary site. As an alternative, this 100% data recovery requirement can be avoided and individual files or directories restored if the storage administrator is willing to go through the time consuming process of data classification.
Cloud-Based NAS
File services are a good use case for cloud storage since it’s an application that can take advantage of the cloud’s strong points: near-unlimited scalability, simple implementation and ‘built in’ backup (the data’s already offsite). The cloud option can eliminate the management burden of adding local NAS capacity or additional NAS systems to accommodate data growth. It can also require less expertise and less up-front costs to implement, especially important for smaller IT organizations. Finally, cloud storage essentially has data protection included, since the data’s already offsite.
There are several ways to implement cloud-based file services. A common solution is to install a ‘hybrid’ server appliance or cloud gateway locally to provide cloud protocol translation and caching to improve performance. In a DR situation, this piece of hardware must be replaced before files can be brought back from the cloud and their associated applications restarted. Unless a spare unit is pre-purchased this delay could be significant.
Virtual NAS appliances can be the answer. These solutions download and run on an existing ESX host and provide a viable alternative to a stand alone NAS for its most common use case, user home directories. Virtual NAS appliances provide that functionality but don’t require the installation of yet another storage platform that needs to be managed and maintained. In addition, some virtual NAS appliances like the Nasuni filer provide a backend connection to one or more cloud storage providers. They also use the local storage that’s available in the infrastructure to maintain a cache for the most active files and ensure performance levels comparable to a traditional local file server or NAS. Similarly, in a DR situation, a virtual NAS appliance can be restarted and provide access to files stored in the cloud in minutes.
Restoring a Virtual NAS Appliance
When a disaster occurs a new copy of the virtual NAS appliance software can be either downloaded or produced from a local storage device. With the new virtual appliance installed, the administrator provides encryption keys and logins for the cloud storage provider and the NAS system is up and running. Users and applications can ‘see’ their files even though none of them have been physically restored at this point. The files are recovered as they are accessed creating essentially an on-demand recovery process. This results in the most important files being returned to the users quickly, while the rest stay in the cloud until needed. This is important because it means the storage administrator doesn’t need to go through a data classification procedure, since the restore-on-access process creates that classification automatically.
Effective disaster recovery is critical for file systems, just as it is for databases. The alternatives for providing local file services - stand alone NAS systems, general purpose OS file servers or virtual, general purpose OS file servers - have weaknesses when it comes to DR. Most require either the physical transportation of a storage ‘container‘ or a WAN-based replication infrastructure to get data offsite. On the recovery side, these solutions can experience significant delays as the containers must be physically returned from the remote location and then in many cases, the files must be restored using the backup application. A hybrid gateway appliance can provide a cache on the front end, cloud storage on the back end and consolidate file services for the environment. But if a disaster occurs restoring this physical system may take too long as well.
A virtual NAS appliance, like the Nasuni filer, can be a way to sidestep many of these shortcomings when it comes to DR for NAS devices. It can combine the rapid recovery advantages of a VM-based file server with the scalability of cloud storage and remove the need for data backup in the process. Like the hybrid cloud appliance, the front end cache will fill as files are accessed from the cloud, providing ‘local NAS’ performance. But since there’s no physical storage device to replace or set up, the virtual NAS appliance can provide affordable NAS DR in a few minutes.
Nasuni is a client of Storage Switzerland
Eric Slack, Senior Analyst
